TY - GEN A1 - Fritsche, Chris A1 - Eckart, Sven A1 - Shrestha, Krishna Prasad A1 - Mauß, Fabian A1 - Krause, Hartmut T1 - Methane flames with a substitution of 50 to 100 percent hydrogen: Experimental and numerical investigation of the temperature and pressure dependence of the laminar burning velocities T2 - 10th European Combustion Meeting, Proceedings of the European Combustion Meeting N2 - This work reports the laminar burning velocities for CH4/H2 blends in mixtures with air utilizing the constant volume chamber at temperatures from 300 to 423 K, pressures from 2 to 10 bar and equivalence ratios from 0.7 to 2.4. A detailed chemical kinetic model based on our previous work is used to reproduce the experimental data. The chemical kinetic model can reproduce the experimental data better at lean conditions compared to rich conditions. It is observed that with an increase in H2 fraction in fuel blend, laminar burning velocities increase. Model reveals that with increasing H2 fraction in the fuel blend, formation of key radicals H, OH and O are promoted leading to higher laminar burning velocities. The most sensitive reactions are O2+H=OH+O, CO+OH=CO2+H, CH4+H=CH3+H2 and CH4+OH=CH3+H2O. It is found that as initial mixture temperature increases, the laminar burning velocity increases and shows a linear trend whereas this trend is reversed as the initial pressure increases. KW - Methane KW - Hydrogen KW - Kinetic Model KW - Laminar burning velocity KW - Constant Volume chamber Y1 - 2021 UR - https://www.researchgate.net/publication/358415279_Methane_flames_with_a_substitution_of_50_to_100_percent_hydrogen_Experimental_and_numerical_investigation_of_the_temperature_and_pressure_dependence_of_the_laminar_burning_velocities ER - TY - GEN A1 - Fritsche, Chris A1 - Shrestha, Krishna Prasad A1 - Eckart, Sven A1 - Mauß, Fabian A1 - Krause, Hartmut T1 - Temperature and pressure dependency of the burning velocity in laminar premixed methanol and polyoxymethylene dimethyl ether (OME1, OME2, and OME3) flames T2 - 10th European Combustion Meeting, Proceedings of the European Combustion Meeting N2 - This work reports the laminar burning velocities (LBV) for the liquid fuels methanol, and polyoxymethylene dimethyl ethers (OMEn, n = 1-3) in mixtures with air utilizing the heat flux burner and constant volume chamber at temperature 393 to 443 K, pressure 1 to 10 bar, and equivalence ratio 0.6 to 1.9. Laminar burning velocities for OME2 and OME3 higher than 1 bar are reported for the first time. A detailed chemical kinetic model for OME2 and OME3 was developed based on our previous work utilizing experimental data from this work. Overall, model predictions are in good agreement with the experimental data. It is previously shown that with increases in unburned gas temperature laminar burning velocity increases and shows a linear trend with respect to temperature. Further, laminar burning velocity decreases with an increase of initial pressure. The dependence of burning velocity is not linear for all the fuels investigated. For comparable temperature and pressure conditions, it was found that with an additional CH2O group the laminar burning velocities increase marginally and there is no shift of maximum laminar burning velocity with respect to equivalence ratio. KW - Oxymethylene ethers KW - Lamianr burning velocity KW - Kinetic Modeling KW - heat flux burne KW - constant volume chamber Y1 - 2021 UR - https://www.researchgate.net/publication/358415681_Temperature_and_pressure_dependency_of_the_burning_velocity_in_laminar_premixed_methanol_and_polyoxymethylene_dimethyl_ether_OME1_OME2_and_OME3_flames ER - TY - GEN A1 - Shrestha, Krishna Prasad A1 - Seidel, Lars A1 - Zeuch, Thomas A1 - Mauß, Fabian T1 - Modeling of NOx Formation and Consumption during Oxidation of Small Alcohols T2 - 9th European Combustion Meeting, Proceedings of the European Combustion Meeting N2 - This work presents a newly developed kinetic mechanism extending our recent work (Shrestha et al. [1]) for the oxidation of methanol and ethanol and their fuel interaction with NO x chemistry in jet-stirred reactors, flow reactors, and burner-stabilized premixed flames. The work mainly focuses on fuel interaction with nitrogen chemistry and NO formation in laminar premixed flames. It is found that for methanol oxidation in jet-stirred reactor doping of the fuel blends with NO increase the reactivity of the system by increasing the net production of OH radicals. The increased amount of OH is formed via NO/NO 2 interconversion reaction channels NO+HO 2 ⇋NO 2 +OH, NO 2 +H⇋NO+OH, NO 2 +HO 2 ⇋HONO+O 2, followed by the thermal decomposition of HONO producing NO and OH. In burner-stabilized premixed flames studied here for methanol/air and ethanol/air, NO is mainly formed via the NCN route (CH+N 2 ⇋NCN+H) and minor contribution comes from the NNH route (NNN⇋N 2 +H). Y1 - 2019 UR - https://hal.archives-ouvertes.fr/hal-02334906 ER - TY - GEN A1 - Shrestha, Krishna Prasad A1 - Mai, Tam V.-T. A1 - Giri, Sushant A1 - Giri, Binod Raj A1 - Huynh, Lam Kim A1 - Mauss, Fabian T1 - Reaction Kinetics of NH2 Radicals with Dimethyl Ether (DME) and Diethyl Ether (DEE) and Their Implications in NH3-DME/DEE blend modeling T2 - Los Alamos National Laboratory (LANL) N2 - The reactions of amino radicals (NH2) play a vital role in governing the combustion behaviour of various nitrogen-rich chemical systems such as ammonia, coal nitrogen gasification, and biomass. Ammonia has recently gained considerable attention in the combustion community. Since it is a carbon-free fuel, it can help combat global warming by decarbonizing the energy sectors. However, several reports in the literature highlight the importance of the NH3-dual fuel approach to boost the combustion properties of neat ammonia. For combustion modeling of NH3-dual fuel systems, accurate knowledge of the cross-reactions between the nitrogen and carbon family is very critical. Several earlier studies have shown the influence of NH2 radical reactions with the fuel (combustion promoter) in accurately predicting the low- temperature combustion behaviour of NH3-dual fuels (see Giri et al. and references cited therein). The reactions of NH2 radicals are not only important in the combustion environment but also, they are relevant to the chemistry of planetary atmospheres. In this work, we investigated the hydrogen abstraction reactions of NH2 radials with dimethyl ether (DME) and diethyl ether (DEE) using a high-level quantum method combined with the statistical rate theory. We implemented the derived rate coefficients in our kinetic model to identify its effect in the combustion modeling of NH3-DME/DEE blends. Y1 - 2023 UR - https://www.osti.gov/biblio/1987392 IS - LA-UR-23-26969 ER - TY - GEN A1 - Franken, Tim A1 - Seidel, Lars A1 - Gonzalez Mestre, Laura Catalina A1 - Shrestha, Krishna Prasad A1 - Matrisciano, Andrea A1 - Mauss, Fabian T1 - Assessment of Auto-Ignition Tendency of Gasoline, Methanol, Toluene and Hydrogen Fuel Blends in Spark Ignition Engines T2 - THIESEL 2020 Conference on Thermo-and Fluid Dynamic Processes in Direct Injection Engines N2 - State of the art spark ignited gasoline engines achieve thermal efficiencies above 46 % e.g. due to friction optimized crank trains, high in-cylinder tumble flow and direct fuel injection. Further improvements of thermal efficiency are expected from lean combustion, higher compression ratio and new knock-resistant fuel blends. One of the limitations to these improvements are set by the autoignition in the end gas, which can develop to knocking combustion and severely damage the internal combustion engine. The auto-ignition is enhanced by high cylinder gas temperatures and reactive species in the end gas composition. Quasi-dimensional Stochastic Reactor Model simulations with detailed chemistry allow to consider the thermochemistry properties of surrogates and complex end gas compositions. Based on the detailed reaction scheme and surrogate model, an innovative tabulated chemistry approach is utilized to generate dual-fuel laminar flame speed and combustion chemistry look-up tables. This reduces the simulation duration to seconds per cycle, while the loss in accuracy compared to solving the chemistry “online” is marginal. The auto-ignition events predicted by the tabulated chemistry simulation are evaluated using the Detonation Diagram developed by Bradley and co-workers. This advanced methodology for quasi-dimensional models evaluates the resonance between the shock wave and reactionfront velocity from auto-ignition in the end gas and determines if it is a harmful developing detonation or normal deflagration. The aim of this work is to evaluate the auto-ignition characteristics of different fuel blends. The Stochastic Reactor Model with tabulated chemistry is applied to perform a numerical analysis of the autoignition of the fuel blends and operating conditions. Experimental measurements of a single cylinder research engine operated with RON95 E10 fuel are used to train and validate the simulation model. The RON95 E10 fuel is blended with Methanol, Hydrogen and Toluene. The knock tendency based on the evaluation of auto-ignition events of the different fuel blends are analysed for three operating points at 1500 rpm 15 bar IMEP, 2000 rpm 20 bar IMEP and 2500 rpm 15 bar IMEP with advanced spark timings. Y1 - 2020 UR - https://hal.science/hal-03573870 ER - TY - GEN A1 - Mante, Till A1 - Prehn, Sascha A1 - Theile, Martin A1 - Seidel, Lars A1 - Mestre, Laura A1 - Buchholz, Bert A1 - Mauß, Fabian ED - Heintzel, Alexander T1 - Investigation of An Ammonia Diesel Dual-Fuel Combustion Process on a Heavy-Duty Single Cylinder Research Engine for the Development of Suitable Simulation Tools for Maritime Applications T2 - Heavy-Duty-, On- und Off-Highway-Motoren 2022 : Stand der Energiewende im Heavy-Duty-Bereich N2 - This paper discusses the adaption of a single cylinder research engine for a retrofit application with an ammonia diesel dual-fuel combustion process and the build of an ammonia fuel system. The gaseous ammonia will be injected in the air intake pipe and the premixed ammonia air mixture will enter the combustion chamber. The diesel injection is carried out via a high-pressure common rail system. All relevant parameters can be freely adjusted via a freely programmable control unit. With the help of experimental data from a single cylinder research engine at the chair of piston machines and internal combustion engines of the University of Rostock (LKV), a dual-fuel combustion model based on detailed chemistry will be developed and optimized. This model will be integrated in a full research engine model, which ensures the best possible representation of the real engine. The combustion model is being developed by LOGE Deutschland GmbH. The full research engine model is developed by FVTR GmbH. The analysis of the combustion process starts with pure diesel operating points and is successively substituted by ammonia in the course of the measurement campaigns. Both the combustion characteristics are relevant, as they significantly influence the resulting performance and engine operation, as well as the exhaust emissions, as the carbon emissions can be reduced, but the nitrogen oxides and ammonia slip increase significantly in relevance due to the ammonia. The results obtained will be used to derive initial recommendations for action and to estimate the potential for application in the inland waterway shipping. In addition, the development of the systematic simulation tools covers a broad spectrum of research questions and aims to increase the efficiency of the necessary R&D. Y1 - 2022 SN - 978-3-658-41477-1 SN - 978-3-658-41476-4 U6 - https://doi.org/10.1007/978-3-658-41477-1_3 SP - 24 EP - 39 PB - Springer Vieweg CY - Wiesbaden ER -